Locking apparatus for elevator platforms



March 16, 1948. 'c. A. DANA 2,437,999

LOCKING APPARATUS FOR ELEVATOR PLATFORMS Filed Feb. 28, 1946 4 Sheets-Sheet l l I I I I /Z0 I l I I: ,/5 4 F1 /7 l i l ll Ca /a 55 49 V V o Z8 34 WITNESSES: 33 r INVENTOR RNEY fifiW Char/e a 5? Dana.

C. A. DANA March 16, 1948.

LOCKING APPARATUS FOR ELEVATOR PLATFORMS Filed Feb. 28, 1946 4 Sheets-Sheet 2 m Qd Mao

INVENTOR WITN ESSES: 5Q7

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n V 4 ORNEY Patented Mar. 16, 1948 LOCKING APPARATUS FOR ELEVATOR PLATFORMS Charles A. Dana, North Plainfield, N. J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 28, 1946, Serial No. 650,950

9 Claims.

My invention relates to locking apparatus for elevator platforms and more particularly to means for locking large elevator platforms in position at a floor landing.

One object of my invention is to provide a mechanical interlocking means for preventing a locking operation of the looks at an elevator parking floor when the elevator platform is not at that floor.

Another object is to provide a mechanical interlocking for maintaining the locks at a parking floor at which an elevator platform is parked in their locking position when the means for raising and lowering the platform does not have sufficient power to fully support the platform.

It is also an object to provide an interlocking mechanism at a parking floor for an elevator platform which will prevent any dangerous operation of the locking mechanism at that floor, either when the platform is at that floor or is away from that floor.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which:

Figure 1 is a view in aft end elevation of a deck edge elevator for an airplane carrier ship, with the elevator platform disposed at the lower deck;

Fig. 2 is a view of the elevator illustrated in Fig. 1, in side elevation, taken from the inside of the ship and looking in the outboard direction, with the platform at the upper deck;

Fig. 3 is an enlarged top-plan view of the elevator platform locked in position at the upper or 'flight deck, part of the deck being broken away to disclose my improved locking apparatus and interlocking mechanism and with the platform shown in broken parts to conserve space.

Fig. 4 is an enlarged view in fore end elevation of the interlocking mechanism illustrated in Fig. 3;

Fig. 5 is an enlarged sectional view in side elevation of the fore interlocking lever and its connection to the fore locking bar as illustrated in Fig. 4 looking in toward the hull of the ship, and

Fig. 6 is taken on the line VI-VI of Fig. 5, to give a top plan view of the interlocking lever at the fore end of the elevator.

The invention is illustrated as applied to a deck edge elevator on an airplane carrier ship. In

a typical ship of this character, the flight deck overhangs the edge of the ship about 16 feet and out of this overhanging part is notched a space for an elevator platform. Such a platform may be about feet long and about 34 feet wide and may weigh as much as 60 tons. The outboard portion of the platform may extend approximate- 1y 18 feet beyond the overhanging edge of the flight deck.

Although the invention is described in connection with a deck edge elevator, it may be used in connection with any movable body which should be securely locked in particular position.

Referring more particularly to Figs. 1, 2 and 3, I have illustrated a deck edge elevator comprising a truss or base section. It provided with a platform section II disposed between a pair of guide rails l2 and I3 mounted on the outer side of a ship hull M for serving its lower or main deck l5 and its upper or flight deck It. An upper roller l1 and a lower roller I8 are rotatably mounted on each end of the base section In in position to ride in vertical guiding slots l9 and I9a in the sides of the guide rails facing each other for guiding the vertical movement of the elevator as it is raised or lowered and for maintaining the base section in its desired angular relation to the hull of the ship.

A plurality of hoisting cables 20 and 20a, operated by a hydraulic hoisting engine 2|, are provided for supporting the elevator platform and base and for raising and lowering them. The hydraulic engine has a single cylinder 22 mounted in a horizontal position on a frame or engine bed 23 and a power plunger 24 with its inner end disposed in the cylinder. The outer end of the plunger is provided with a power head 25 in which a pair of power sheaves 26 are rotatably mounted.

In operation, the plunger moves back and forth horizontally and thus moves the power sheaves 26 back and forth with it, for operating the holsting cables to raise and lower the elevator. The plunger is designed for operation by a suitable hydraulic medium such as oil, placed under ressure by any suitable equipment (not shown) and is controlled by a valve 2! operated by a valve motor 27a which may be controlled by any suitable control apparatus (not shown).

The outer ends of the cables 20 are secured to the aft end of the base section by suitable hitches 28 mounted thereon and pass upwardly and over an idler sheave 29 fastened to the ship structure underneath the overhanging portion of the flight deck, thence inwardly over a second idler sheave 30 mounted on the ship frame inside the hull, thence downwardly and under a deflector sheave 3| mounted on the engine bed 23, thence around a stationary sheave 32 mounted on the engine bed at the rear of the engine, and thence around one of the power sheaves 26 to a plurality of hitches 33 mounted on the underside of the engine cylinder.

The outer ends of the cables 20a are secured to the fore end of the base section by a suitable cable hitch 34 and pass upwardly over an idler sheave 35 fastened to the ship structure underneath the overhanging portion of the flight deck,

thence inwardly over a second idler sheave 36 mounted on the ship frame inside the hull, thence downwardly and under a deflector sheave 31 mounted on the right-hand end of the engine bed, and thence under and over one of the power sheaves 26 in the plunger head to suitable hitches 38 secured to the upper rear part of the enginev cylinder. Although I "have illustrated a hydraulic engine for operating the hoisting cables, it is to be understood that any other suitable engine or motor may be used as a power means for operating th hoisting cables.

The base member l6 comprises a plurality of vertical truss members, such as 43, 44 and 45 and a plurality of angularly disposed trusses, such as 46 and 41. A plurality of inner bracing trusses, such as 48 and 49, are applied to the truss structure for increasing its strength and stability. "The trusses and bracing trusses are constructed of high tensile steel tubing, structural steel and steel plate welded together in bridge-like construction to form a relatively light but strong base for supporting the elevator platform llv and any load which may be placed thereon.

The platform section II is constructed of high tensile steel tubing, such as 56, and 52, welded together in bridge-like construction to form a relatively light but strong frame upon which any suitable flooring 53 may be laid.

The platform section Il may be hinged on the base section 1 0, so that it may be tilted upwardly and stowed against the side of the ship if desired, as is more fully illustrated and described in patent application Serial No. 639,274, filed January 5, 1946. l

A stop block 54 is mounted on the upper face of the cable hitch 28 and a similar block 55 is mounted on the upper face of the cable hitch 34. A dead stop flange 56 is mounted on the underside of the overhanging edge of the upper deck adjacent to the sheave 29 and a similar dead stop flange 51 is mounted on the underside of theoverhanging edge of the upper deck adjacent to the sheave 35. The stop block 54 is disposed to engage the stop flange 56 and the stop block 55 is disposed to engage the stop flange 51 when the elevator platform is raised to its correct position at the upper deck and thereby provide a positive stopping means for the platform at the upper deck to prevent the engine from raising it above its correct position at that deck. Beveled flanges 5S and 59 are provided on the ends of the elevator platform for engaging cooperating beveled flanges 60 and 60a on the flight deck for centering the platform when it is raised to that deck.

An aft lock 6| and a fore lock 62are provided for locking the elevator platform in its parking position at the flight deck whileit isnot in service or when its cables are to be renewed or at any other desirable time.

The fore lock 62 comprises a cylindrical lock bolt 63 disposed to extend through the guide rail 13 and under a projecting block 64 on the platform, an arm 65 for operating the bolt, a shaft 66 for operating the arm and an air engine 61 for operating the shaft. The lock bolt 63 is slidably disposed in a sleeve 68 which is horizontally mounted in the guide rail [3 and held in position by a collar 69. The collar is securely fastened to the guide rail by means of a box-like housing 10 which is mounted on the guide rail by means of a plurality of structural steel plates H to 15, inclusive. These plates are welded to each other and to the guide rail and to the underside of the flight deck to form a strong and sturdy construction. The projecting block 64 is rigidly mounted on the platform section by a plurality of steel tubes 16 and 11 which are welded to the vertical trusses wand 19 which form a part of the platform section 10. The position of the block 64 on the platform frame should be so selected that there will be a clearance of approximately inch to /4 inch between it and the lock bolt when the lock bolt is in its locking position and the platform is pulled tightly against the dead stops 56 and 5'! at the flight deck.

The free end of the arm 65 is connected to the locked bolt by a link while its lower end is firmly fixed on the operating shaft 66. The shaft 66 is rotatably mounted in a pair of bearings 3| and 82 which are supported by structural steel plates 83 and 84 depending from th overhanging edge of the flight deck.

The air engine 6! is supported from the underside of the overhanging flight deck by a structural steel plate 86 and is provided with a piston rod 81 for operating a power head 88 slidably disposed on a pair of slides 89 and 90 attached to the engine. The power head is connected by a link 9i to the upper end of an operating arm 92, the lower end of which is fixed on the rotatable shaft 66 so that operation of the engine in one direction will rock the shaft to withdraw the bolt 63 from its locking position and operation of the engine in the opposite direction will push the bolt forward into locking position. The air engine may be connected for operation to any suitable source of air power (not shown) mounted in the ship.

The lock 6| at the aft end of the platform comprises a lock bolt 93 mounted in the guide rail I2 in position to be moved into and out of lock ing position underneath a lock block 64 on the platform section by an operating shaft 95 and is constructed, mountedand operated in the same manner as the fore lock'62.

An arm 96 is-fixed on the inner end of the operating shaft 95 and its outer end is connected by a rod 9'! to the outer end of an arm 98 fixed on the inner end'of the operating shaft 66 so that rotation of the shaft 66 by the air engine 51 to move the lockbolt 63 into or out oflocking position will also cause the shaft 65 to rotate and thereby move the lock bolt 93 into or out of locking position in accordance with the movement of the bolt 63.

An additional operating rod I60 which may be connected to any suitable manually operative means (not shown) is attached to the free end of an arm 16! mounted on the outer end of the operating shaft 66 so that the locks may be operated by hand when it is not desired to use the air engine for operating them.

When the elevator platform is locked at the 5 flight deck, the locking bolts must not be removed from their locking position unless the hoisting means has sufficient power to maintain the hoisting cables with full power to support the platform at the flight deck. Therefore, I have provided mechanical interlocking mechanisms I03 and I04 for preventing movement of the lock bolts from their locking positions when the power of the hoisting engine is not sufficient to support the elevator platform and hold it tightly against the dead stops 55 and 51.

The safety mechanism I at the fore end of the elevator comprises a locking shoulder or notch me'ans having a fixed connection with the bolt 63, such as a notched cam I05, an interlocking lever I06, a biasing device, such as a spring I01, and an operating bracket head I08. The upper end of the cam I05 is attached to the operating shaft 56 and its free end extends downwardly between a pair of housing plates I09 and H0 which are welded to the supporting plate 83 attached to the overhanging edge of the flight .deck. The cam moves with the shaft 56 and its lower end is provided with an unlocked notch I I I and a locked notch I I2.

The interlocking lever I00 is pivotally mounted on the guide rail I3 by a pivot pin H0 with its outer end extending through a slot I i5 in a steel plate H6 attached to the steel plates I4 and I5 mounted on the guide rail. The length of the slot H5 limits the downward movement of the interlocking lever when it is freed from its operating devices. A horizontal rectangular-like frame II'I of steel plate is attached to the outer end of the lever I05 by a plurality of bolts H8 in position to surround the lower ends of the housing plates I00 and III] and the lower end of the cam I05. A latching device or cross bar H9 is welded in and extends across the frame H1 at right angles to the body of the lever I00. The position of the cross bar and the position of the notches III and H2 are so arranged that the cross bar may enter the notch I H when the lock bolt 03 is withdrawn from its locking position or it may enter the notch H2 when the lock bolt 63 is in its locking position. A suitable guide slot I20 is disposed in the housing plate I09 and a similar slot is provided in the housing plate H0 for guiding the cross bar in its up and down movements.

The compression spring I0! is provided for biasing the cross bar upwardly toward the notches I I I and H2 and is concentrically mounted on the upper end of a rod I22, the lower end of which is pivotally attached to a block I23 welded to the outer end of the rectangular frame I IT. The spring is disposed between a nut I24 on the rod and a steel plate I25 which is welded to and extends from the upper ends of the housing plates I09 and H0 so that the spring will exert a constant biasing upward pull on the outer end of the interlocking lever I06 to force the cross bar H9 into the one or the other of the notches III and H2.

The bracket head I08 is mounted on the upper end of an adjustable screw threaded bolt I21 disposed in a screw threaded aperture in a body I28 mounted on the outer ends of a pair of bracket arms I29 and I30, the inner ends of which are welded to the vertical truss I8 forming a part of the frame of the platform section so that the bracket head will move with the platform section. A nut I3I is provided for securing the bolt I21 in the position to which it may be adjusted in the body I28.

The bracket head should be so mounted in the platform section that it will engage the inner end of the interlocking lever I06 and move it upwardly when the elevator platform is hoisted upwardly to the flight deck and held tightly against the dead stops 5B and 51 by the hoistmg engine and thereby move the frame H'I downwardly and thus move the cross bar H9 downwardly against the pull of the biasing spring I01 and out of engagement with the cam I05.

The interlocking mechanism I03 disposed at the aft end of the platform is constructed in the same manner as the fore interlocking mechanism I00 and has its interlocking lever I06 for locking the shaft 95 pivotally mounted by a pivot pin H40. on the guide rail I2 in position to be operated by a bracket head I08a attached to the vertical truss 18a of the platform frame.

The positions of the levers I05 and I00a, with relation to their cooperating bracket heads IBM and the distances between the lock bolts 03, 93 and the stop blocks 64, 94 should be so selected and arranged that when the elevator platform is against the dead stops 56 and 51, the interlocking levers I06 and I06a will hold the cross bars H9 out of the locking notches, but, when the platform is lowered to rest on the lock bolts in their locking position, the interlocking levers will push their cross bars to the locked position notches in the cams and prevent unlocking of the lock bolts.

Assumed operation of the apparatus It will be assumed that the elevator platform is at the upper deck, as shown in Fig. 2, that the hoisting engine 2I is holding it tightly against the dead stops 56 and 51 and that the lock bolts 53 and 93 are in looking position, as shown in Fig. 3. Under these conditions, there is a clearance of from s inch to A inch between the lock bolt 53 and the lock block 64 and between the lock bolt 93 and the lock block 94. Also the bracket heads I08 and I08a have raised the inner ends of the interlocking levers I05 and I05a to release the locking shafts 66 and 95.

It will be assumed now that the air engine 6'! is operated to unlock the bolts 63 and 93. As the air engine operates, its power head moves inward- 1y thus pulling on the link 9i and the arm 92 to rock the shaft 50 and thus move the arm 65 to Withdraw the bolt 63 from its locking position. The rotation of the shaft 06 also operates its arm 98 and thus rotates the shaft 95 by means of the rod 91 and the arm 90 to move the bolt 93 out of its locking position. As the shaft 60 rotates to its unlocked position, it moves its cam I05 to a position where its notch III may be entered by the cross bar H9. Likewise, the rotation of the shaft 95 moves its interlocking mechanism where the unlocked notch in its cam may be entered by its cross bar due to operation of the interlocking lever I06a.

It will be assumed now that the hydraulic engine 2| is operated to lower the platform to the lower deck. As the platform moves downwardly, the bracket heads I08 and I08a leave the ends of t the levers I00 and I06a and thus release them to the platform is away from'the flight deck. The biasing spring lfl'la on the mechanism 103 also operates in the same manner to effect the locking of the shafts 95 and 96 by reason of the connecting rod 97 and the arms 96 and 98. Locking of either the shaft 56 or the shaft 95 will lock both shafts.

It will be assumed now that the platform has moved to and stopped at the lower deck and that the hydraulic engine 2! is operated to move it to the upper deck. As the platform approaches closely to the upper deck and moves into engagement with the dead stops 56 and 5?, the bracket heads IE8 and i-Jila engage the inner ends of the interlocking levers Hi5 and I850. and move them upwardly thereby releasing the operating shafts 66 and 95 so that the locked bolts E23 and 93 may be operated to lock the platform at the upper deck, if desired. The movement of the lever 1% effects its release of the shafts B5 and 55 by moving the cross bar H9 downwardly out of the notch H I so that the cam IE5 is free to move with the shaft 66. The movement of the interlocking lever [96a effects its release of the shafts 95 and 56 by moving its corresponding cross bar downwardly in the same manner. Both lock bolts 63 and 93 may now be moved to their locking position if desired.

It will be assumed now that the platform is held tightly against the dead stops 56 and 57 at the flight deck and that the air engine 51 is operated to move the lock bolts 53 and 93 into their locking position to lock the platform at the flight deck. If the air engine is operated, its power head 88 pushes outwardly against the arm 92 and thereby rocks the shaft 56 and the shaft 95 to cause the arms 35 and 65a to push the lock bolts 63 and 93 into their locking positions. The rocking movement of the shaft 66 moves its cam 35 to a position where the cross bar I i 9 may enter its slot H2 if the platform should move downwardly to a slight extent. The rocking movement of the shaft 95 effects a similar action in the interlocking mechanism i 93.

It will be assumed now that the attendants desire to leave the platform at the upper deck for some time and shut down the hydraulic engine 2i or that the power of the engine decreases to such an extent that it fails to hold the platform tightly against the flight deck. In either case the platform will leave its position against the dead stops and, as it settles down on the lock bolts 83 and Q3, its bracket heads [88 and Wild will leave the inner ends of the interlocking levers its and Illfia and thus free them for operation by their biasing springs i8? and lilla.

As the inner end of the lever N35 is free from the upward pressure of the bracket head H38, the biasing spring IQ! raises its outer end or frame ill and thereby moves its cross bar I93 into the notch H2 in the cam Hi5 and thereby locks the shaft 66 and also the shaft 55 against any rocking movement to move the lock bolts out of their locking positions. The freeing of the inner end of the lever lfifia by the downward movement of the bracket head 158a also permits its biasing spring 27a to raise the outer end of that lever and there by also lock the shafts 95 and 66 against any rocks ing movement to unlock the lock bolts Q3 and With the operating shafts es and dfilocked against any rocking movement, it will be apparent that the lock bolts 63 and 23 cannot be removed from their locking positions until the hoisting engine develops suflicient power to raise and does raise the elevator platform from its position on the lock 8 bolts until it is held tightly against the dead stops 55 and 51.

From the foregoing operation, it will be apparent that I have provided a very simple and efiicient mechanical means for preventing any locking action of its lock bolts when the platform is away from the flight deck and for preventing any unlocking operation of the lock bolts when the elevator platform is in locked condition at the flight deck and there is insuflicient power on the hoisting engine to support the platform and hold it tightly against the dead stops at the flight deck.

Although I have shown and described only one specific embodiment of my invention, it is to be understood that many modifications thereof and changes therein may be made without departing from the spirit and scope of the invention.

I claim as my invention 1. In an elevator for serving a floor, a hoisting means for the elevator, dead stop means disposed at the floor for positively stopping the elevator thereat, locking means mounted at the floor for locking the elevator to within a preetermined distance of the floor, and interlocking means responsive to movement of the elevator a predetermined distance from the dead stop means while the locking means is in its locking position for preventing unlocking operation of the locking means.

2. In an elevator, a platform for serving a parking floor, dead stop means at the parking floor for stopping the platform thereat, a hoisting engine for operating the platform and holding it against the dead stop means, locking means mounted at the floor for locking the platform within a predetermined distance of that floor, means for operating the locking means into and out of locking position, and means responsive to movement of the platform a predetermined distance from the dead stop means While the locking means is in locking position for preventing withdrawal of the locking means from its looking position and responsive to movement of the platform a greater predetermined distance away from the dead stop means while the locking means is in its unlocked position for preventing movement of the locking means to its locking position.

3. In an elevator, a platform for serving a parking floor, a dead stop at the parking floor at each end of the platform for stopping the platform thereat, a hoisting engine for operating the platform and holding it against the dead stop, a lock mounted at the parking floor for each end of the platform, means for moving the looks into and out of locking position, and means responsive to movement of the platform a predetermined distance from the dead stops while the locks are in looking position for preventing withdrawal of the looks from their locking position.

4. In an elevator, a platform for serving a parking floor, a dead stop at the parking floor at each end of the platform for stopping the platform thereat, a hoisting engine for operating the platform and holding it against the dead stops, a lock block mounted on each end of the platform, a lock bolt mounted at the parking floor for each end of the platform and disposed to extend under the lock block at that end of the platform and a predetermined distance from it when moved into locking position, when the platform is against the dead stops, means for moving the locking bolts into and out of locking position, and means responsive to movement of the platform. a predetermined distance from the dead stops while the lock bolts are in locking position for preventing withdrawal of the lock bolts from their locking position and responsive to movement of the platform away from the dead stops while the lock bolts are in their unlocked position for preventing movement of the bolts to their locking position.

5. In an elevator, a platform for serving a parking floor, dead stop means at the parking floor for stopping the platform thereat, a hoisting engine for operating the platform and holding it against the dead stop means, a lock block mounted on each end of the platform, a lock bolt mounted at the parking floor for each end of the platform and disposed to extend under the lock block at that end of the platform and a predetermined distance under it when moved into locking position, means for moving the locking bolts into and out of locking position, an interlocking lever pivotally mounted on the ship at each end of the platform for interlocking the lock bolts, means for biasing the levers into position for preventing a locking operation of the bolts or an unlocking operation of the bolts, and bracket heads mounted on the platform and responsive to movement thereof for moving the levers against their biasing means when the car is within a predetermined distance of the parking floor and thereby freeing the bolts for locking or unlocking movement.

6. In a deck edge elevator for an airplane carrier ship, an elevator platform for serving a main deck and a flight deck, a hoisting engine for supporting and raising and lowering the platform, a pair of dead stops mounted at the flight deck, one for each end of the platform, a lock bolt mounted on the ship for each end of the platform, a lock shaft rotatably mounted on the ship at each end of the platform for operating the lock bolts to locking position and to unlocking position, a cam fixed on each lock shaft, an interlocking lever pivotally mounted on the ship at each end of the platform for engaging the cam thereat, and holding it in its locked position or its unlocked position, means for biasing each interlocking lever toward its associated cam, and a bracket head mounted on each end of the platform for operating the interlocking lever for that end away from its associated cam when the platform approaches closely to the dead stops and for releasing that lever for operation by its biasin means when the platform moves downwardly a predetermined distance from the dead stops.

7. In a deck edge elevator for an airplane carrier ship, an elevator platform for serving a main deck and a flight deck, a hoisting engine for supporting and raising and lowering the platform, a pair of dead stops mounted at the flight deck, one for each end of the platform, a lock block mounted on each end of the platform, a lock housing mounted at the flight deck at each end of the platform, a lock bolt slidably disposed in each lock housing in position to be moved into locking position a predetermined distance below the lock block at its end of the platform when the platform is held against the dead stops, a lock shaft rotatably mounted on the ship at each end of the platform and operably connected to the lock bolts, means for rocking the lock shafts to move the lock bolts into or out of locking position, a notched cam fixed on each shaft and provided with a notch for the locked position of the lock bolt associated with that shaft, an interlocking lever pivotally mounted on the ship at each end of the platform and provided with a latching lever for the cam thereat, a spring for each lever for biasing its latch end toward the notch in the cam associated with it, and a bracket head mounted on each end of the platform for operating the interlocking lever for that end to move its latch bar away from the notch in the associated cam when the platform is moved to the dead stops at the flight deck and for releasing that lever for operation by its biasing spring when the platform moves downwardly a predetermined distance from the dead stops, whereby the latch bars will enter the notches when the lock bolts are in locking position while the platform is at the flight deck and the engine is unable to hold it against the dead stops and thus prevent unlocking of the bolts until the engine can raise the platform against the flight deck and the bolts are moved to their unlocking position.

8. In a deck edge elevator for an airplane carrier ship, an elevator platform for serving a main deck and a flight deck, a hoisting engine for supporting and raising and lowering the platform, a pair of dead stops mounted at the flight deck, one for each end of the platform, a lock housing mounted at the flight deck at each end of the platform, a lock bolt slidably disposed in each lock housing in position to be moved into locking position to lock the platform at the flight deck, a lock shaft rotatably mounted on the ship at each end of the platform and operably connected to the lock bolts, means for rocking the lock shafts to move the lock bolts into or out of locking position, a cam fixed on each shaft and provided with a locked notch for the locked position and an unlocked notch for the unlocked position of the lock bolt associated with that shaft, an interlocking lever pivotally mounted on the ship at each end of the platform adjacent to the cam 'thereat, means for biasing each lever toward the notches in the cam associated with it, and a bracket head mounted on each end of the platform for operating the interlocking lever for that end to move it away from the notches in the associated cam when the platform approaches closely to the dead stops and for releasing that lever for operation by its biasing spring when the platform moves downwardly a predetermined distance whereby the levers will engage the locking notches if the lock bolts are in locked position and will engage the unlocked notches when the platform is at least a predetermined distance away from the flight deck.

9. In a deck edge elevator for an airplane carrier ship, an elevator platform for serving a main deck and a flight deck, a hoisting engine for supporting and raising and lowering the platform, a pair of dead stops mounted at the flight deck, one'for each end of the platform, a lock block mounted on each end of the platform, a lock housing mounted at the flight deck at each end of the platform, a lock bolt slidably disposed in each lock housing in position to be moved into locking position a predetermined distance below the lock block at its end of the platform when the platform is held against the dead stops, a lock shaft rotatably mounted on the ship at each end of the platform and operably connected to the lock bolts, means for rockin the lock shafts to move the lock bolts into or out of locking position, a notched cam fixed on each shaft and provided with a locked notch for the locked position and an unlocked notch for the unlocked position of thelock bolt associated with that shaft, an interlocking lever pivotally mounted on the ship at each endv of the platform and provided with a latching bar for the cam thereat, a spring for each lever for biasing its latch bar toward the notches in the cam associated with it, and a bracket head mounted on each end of the platform for operating the interlocking lever for that end to move its latch bar away from the notches in the associated cam when the platform moves to the dead stops atthe flight deck and for releasing that lever for operation by its biasing 

